In recent years, a distance meter has come to be installed in vehicles. The distance meter measures a distance between an own vehicle and a vehicle immediately on the front side of the own vehicle (hereinafter referred to as “preceding vehicle”) and detects as to whether an inter-vehicle distance is proper.
In one form of the distance meter, laser light is used. The laser distance meter irradiates laser light in a forward direction of the vehicle and receives reflected light to calculate a distance.
The laser light is advantageous for its high rectilinear advancing property and non-diffusing performance. The laser distance meter is mounted on the vehicle by using a bracket. The bracket inevitably involves product dispersion caused due to manufacture thereof. In addition, a mounting error may occur when the bracket is mounted on the vehicle or when the laser distance meter is mounted on the bracket.
Depending on the product dispersion and the mounting error, a risk may arise that an optical axis of the laser distance meter mounted on the vehicle deviates from a predetermined angle. If the optical axis deviate from the predetermined angle, the reliability of a detected distance will decrease. The laser distance meter therefore needs an inspection as a single component and an additional inspection in an on-vehicle state.
Methods for inspecting an optical axis angle of a camera mounted on the vehicle are known (see, for example, Patent Document 1, FIG. 1).
FIG. 10 herein is a view explanatory of a conventional optical axis inspection device for on-vehicle cameras, in which a vehicle 100 includes a camera 101 mounted thereon. The vehicle 100 is carried on a horizontal base 102, and a mirror 103 is standing upright at one end of the horizontal base 102. The mirror 103 is used for evaluating an optical axis 104 of the camera 101.
By replacing the camera 101 with a laser distance meter, it is possible to evaluate an optical axis of the laser distance meter.
The mirror 103 is disposed on a front side of the vehicle 100 at a distance corresponding to about half the length of the vehicle 100. Because the vehicle length is about 6 meters, the mirror 103 is raised to the position about 3 meters forward from the vehicle 100. As a result, the inspection device becomes long.
Due to the demand for compactification of an inspection device and reduction of an inspection area, it is necessary for an inspection device to have a shorter length along a line.